The purpose of this project is to investigate in conscious primates the role of the central nervous system in (1) integrating sensory inflow from thermoreceptor neurons, and (2) activating neural and hormonal regulatory mechanisms concerned with changes in temperature and metabolism. Emphasis will be placed on coordination by the CNS of multiple systems which alter rate of heat loss and gain, and, thus, precisely regulate body temperature. Responses of conscious baboons to thermal challenges such as peripheral and/or hypothalamic-medullary- spinal canal heating and cooling, discrete surgical or pharmacological lesions in the diencephalon, and microinfusion of biogenic amines or prostaglandins into the third brain ventricle or hypothalmic tissue, will be investigated in terms of neuroendocrine, metabolic, and cardiovascular function. During experiments measurements will be made of circulating blood levels of hormones concerned with translocation of substrates, and substrate levels per se. Neuromuscular reactions to thermal challenge, such as shivering and activity will be monitored. Cardiovascular responses will be studied by pressure and rate recording devices. In addition, hypothalamic mechanisms which regulate the anterior pituitary gland in reproduction and lactation will be investigated by systemic and hypothalamic administration of monoamine neurotransmitters, pharmacological stimulating and blocking agents, and target gland hormones. Emphasis will be placed on elucidating patterns of hormone interactions in regulation of metabolism in thermal stress, and in experimental diabetes mellitus.